Showing papers by "Hector M. Guzman published in 2013"

Caribbean coral growth influenced by anthropogenic aerosol emissions

Abstract: Multi-decadal variability in coral growth rates has been documented throughout the Caribbean over the past 150–200 years. Analyses of observational and model data suggest that anthropogenic aerosols were a key driver of variations in coral growth in the western Caribbean in the second half of the twentieth century.

Species composition and bathymetric distribution of gorgonians (Anthozoa: Octocorallia) on the Southern Mexican Pacific coast

Abstract: Gorgonians are important components of coastal ecosystems, as they provide niches, natural compounds with medical applications and are used as bioindicators. Species composition and assemblage structure of gorgonians (Anthozoa: Octocorallia) were studied along a bathymetric profile in the Southern Mexican Pacific coast. Species composition was based on specimens collected within a depth range of 0-70m in 15 sites. The relative abundance of species was determined in six sites at four depths (5, 10, 20 and 25m) using three 10m2 transects at each depth level. Twenty-seven species of gorgonians belonging to six genera and three families were registered. The species composition varied with depth: 11 species were distributed between 0-25m depth, while 17 species were found between 40-70m depth interval. The shallow zone is characterized by a relatively large abundance of gorgonians, dominated by colonies of Leptogorgia cuspidata and L. ena. In contrast, the deepest zone was characterized by relatively low abundance of gorgonians, dominated by L. alba, the only species observed in both depth intervals. The similarity analysis showed differences in the composition and abundance of species by depth and site, suggesting that the main factor in determining the assemblage structure is depth. Results of this study suggest that the highest richness of gorgonian species in the study area may be located at depths of 40-70m, whereas the highest abundances are found between 5 and 10m depth. This study represents a contribution to the poorly known eastern Pacific gorgonian biota.

Two new species of gorgonian octocorals from the Tropical Eastern Pacific Biogeographic Region (Cnidaria, Anthozoa, Gorgoniidae).

Abstract: The gorgoniid Eugorgia is exclusively an eastern Pacific genus. It has a wide geographic and bathymetric range of distribution, found from California to Peru and extends down to 65 m deep. Two new species are herein described. The morphological characters were analyzed and illustrated by light and scanning electron microscopy. Eugorgia beebei sp. n. can be distinguished by its white, ascending, sparse colony growth. Eugorgia mutabilis sp. n. can be distinguished by its white colony that changes color after collection, and the conspicuous sharp-crested disc sclerites. From a morphological point of view the new species are related to the daniana-group, the rubens-group and the siedenburgae-group of Eugorgia; their affiliations, and the proposal of a new group are discussed. These new species increases the number of species in the genus to 15, and contribute to the knowledge of the eastern Pacific octocoral biodiversity.

Decadal increase in seagrass biomass and temperature at the CARICOMP site in Bocas del Toro, Panama

Abstract: The Caribbean Coastal Marine Productivity Program (CARICOMP) was launched in 1993 to study regional long-term interactions between land and sea, taking standardized measurements of productivity and biomass of mangroves, coral reefs and seagrasses. Since 1999 continuous measurements of seagrass (Thalassia testudinum) parameters as well as environmental data have been recorded in Caribbean Panama. Replicate stations were selected near the Smithsonian Tropical Research Institute in Bocas del Toro. Sediment cores and quadrants were placed there to estimate biomass and productivity, respectively. Mean values for productivity, standing crop, turnover rate, total dry biomass, and Leaf Area Index were 1.74gDW/m2/d, 66.6gDW/m2, 2.62%/d, 1 481 gDW/m2, and 4.65, respectively. Total dry biomass (shoots, rhizomes and roots) and LAI of T. testudinum increased significantly during the study period. Mean values for total rainfall, Secchi disk depth, sea surface temperature, and salinity were 3 498mm, 8.24m, 28.79°C, and 32.26psu, respectively. Sea surface temperature was the only environmental variable with a statistically significant change, increasing from 1999 to 2010. Correlation between sea surface temperature and T. testudinum parameters (total biomass and LAI) were both positive and significant. Human population has increased dramatically over the last ten years in Bocas del Toro region, increasing pressure (deforestation, runoff, wastewater) over coastal ecosystems (seagrasses, mangroves, coral reefs). Change in the abundance of T. testudinum may be linked to ocean warming, as a consequence to satisfy plant’s metabolic requirements, although other local factors need to be analyzed (reduced grazing and increased eutrophication). A further warming of the ocean could have a negative effect on T. testudinum population, increasing respiratory demands and microbial metabolism.

A new species of the genus eugorgia (cnidaria: octocorallia: gorgoniidae) from mesophotic reefs in the eastern pacific

Abstract: Our knowledge of octocoral diversity in the eastern Pacific has been focused on shallow reef habitats, while the fauna occurring in the mesophotic zone from 40 to 150 m is poorly known. A new species of the gorgoniid Eugorgia was recently obtained with a submersible from the Hannibal Bank, a coastal seamount 60 km off mainland Panama and 15 km from Coiba Island. The morphological characters were analyzed and illustrated by light and scanning electron microscopy. Eugorgia siedenburgae sp. nov. can be distinguished from the other species in the genus by its bushy, multiplanar, bicolored colony, and the sclerites colors, composition, and sizes. This new species increases the number in the genus to 13 and contributes to our understanding of the fragile mesophotic biodiversity.

The morphology and structure of the Hannibal Bank fisheries management zone, Pacific Panama using acoustic seabed mapping

Abstract: Morfologia y estructura de la zona especial de manejo de Banco Hannibal, Pacifico de Panama mediante el uso de sensores remotos acusticos. The Hannibal Bank sits within the Coiba UNESCO World Heritage Site in Pacific Panama and is also a fisheries management zone. Despite the protected status of the area and the importance of the Bank for commercial fish species such as snapper and tuna, the seamount has received no detailed survey except some collection of organisms. This study mapped the major topographic features and complexity of the Hannibal Bank seamount using acoustic remote sensing. A survey area of around 125km 2 was defined using existing charts and side-scan sonar data were collected during July 2008. A bathymetric output was imported to ArcGIS where a digital bathymetric model and slope map were created. The Benthic Terrain Modeler (BTM) extension for ArcGIS was used to calculate bathymetric position index and rugosity, and used to create a map of zones representing the various seabed morphology zones. The Hannibal bank is an elongated, triangular guyot (flat topped seamount), which ranges in depth from 53m to 416m, covers an area of 76km 2 and is 14.4km long and 7.1km wide. Hannibal bank is composed of steep slopes, more gentle slopes, top of the seamount, crests (elevated ridges at the top of the pinnacles), rugose areas (on crests, top of seamount and slope), gullies and pinnacles. The bank is asymmetric in nature with the Northerly side having a relatively gentle slope with gullies across the surface compared to the SouthWest side which is far steeper and more rugose. There are two pinnacles to the North and South East of the bank that range in depth from 180 to 333m. Rocky substrate makes up 22.6km 2 of the bank and sediment 37.8km 2 . The bank and its steeply sided, rugose areas and pinnacles provide upright structures which can disrupt and topographically enhance currents, increasing productivity. The rugose areas of Hannibal Bank should be primary targets for further research efforts as they may contain corals and their rugosity indicates that these should be some of the highest faunal diversity areas of the bank. Hannibal Bank is likely to come increasing pressure in the future through climate change and fishing and this study has produced valuable information to assist in the future mapping and management of habitats, associated species and fisheries. Rev. Biol. Trop. 61 (4): 1967-1979. Epub 2013 December 01.

Benthic Community Recovery from Small-Scale Damage on Marginal Caribbean Reefs: An Example from Panama

Abstract: The frequency of small-scale physical damage to coral reefs is likely to increase as fishing and tourism pressures intensify. Predicting how reefs will respond to the effects of these types of damage requires empirical exploration, especially on reefs that are already heavily degraded. We replicated small-scale damage on four reefs that live close to their ecophysiological tolerance limits in the Bocas del Toro Archipelago of Caribbean Panama and quantified their recovery over 2 yrs. On each reef we cleared five replicate 1 × 1-m plots of all living benthos simulating physical damage by boat grounding, anchoring, or fishing practices. Recovery of the benthic community was quantitatively monitored and compared to adjacent non-cleared plots (treated as a control) every 6 mo. After 2 yrs, only one of the reefs exhibited evidence of recovery of the cleared plots. Poor recruitment of benthos appeared to slow down recovery of cleared plots on another reef. The other two reefs showed unequivocal shifts toward a macroalgae-dominated system, suggesting that small-scale disturbances could have lasting impacts on marginal reefs. We found no clear contemporary or historical environmental signal that could explain the differential dynamics of recovery amongst these reefs.